A protection control monitoring device takes in an analog input from the outside, converting the analog input into digital data, and thereafter performs various processing to achieve a protection control monitoring function. Further, the protection control monitoring device has a function to store an operating state and data of external inputs when an event occurs, and enables analysis of the states of a power system and a device when an event occurs (see, for example, Reference 1). Accordingly, when the operating state and data of external inputs when an event occurs are stored, it is desired that data used in calculation processing be stored without any change.
When analog input data for a long time are stored, a large number of storage memories are needed. Particularly in a device having a large number of analog input data such as a busbar protective relay device, the necessary capacity increases in proportion to the number of input data. On the other hand, in an incorporated system like the protection control monitoring device, the capacity of the memory for storing data is limited, and there may be a case where storage without any change is impossible.
In such a case, it is generally conceivable to compress the data amount by applying lossless compression. However, in the case of analog input data, fluctuations of values due to random noise exist, and thus there may be cases where compression can be barely performed. Further, by reducing information of random noise through the lossless compression, it is possible to reduce a large amount of data widely. However, in the lossless compression, it is possible that information that is originally needed is reduced besides the random noise, and reproducibility of retained information is lost.
A protection control monitoring device according to one aspect of the embodiments includes a conversion unit sequentially converting analog data corresponding to an amount of electricity of a power system into digital data and outputting the results as a data sequence, a calculation unit sequentially calculating difference data representing a difference between adjacent data in the data sequence and outputting results as a difference data sequence, a data block generation unit dividing each of a plurality of difference data in the difference data sequence into a plurality of partial data, generating data blocks from a plurality of corresponding partial data, and outputting results as a data block sequence, a compression unit losslessly compressing the data block sequence, and a storage unit storing the losslessly compressed data block sequence.